The latest version of Qt, the cross-platform application and UI framework is now available and there's a new version of the Visual Studio tools, the final one from Nokia.

The Qt C++ UI library is well known but its status has changed greatly since Nokia dropped it as the main development environment in favor of Windows Phone 7 and handed over the commercial aspects to Digia PLC. Qt is still being developed by Qt Development Frameworks, which is a Nokia spin-off although the company operates separately and targets other devices as well as those from Nokia.

The stated aim is still to let developers build applications and touch-enabled user interfaces once and then deploy across multiple mobile, desktop, consumer electronic and embedded platforms without having to re-write any code. This doesn't really seem to be in Nokia's commercial interests.

Although Nokia promises to stand behind Qt, there are bound to be doubts about its long term future. A version 5 is planned for next year (2012) but for now version 4.8 has just been released.

The new version of the framework is now available for download for Windows, Linux, and Mac. Those of you using it for Symbian and Nokia N9 will have to wait until January, when targeted versions for these platforms will be available alongside a packaged SDK version.

The highlights of the new version include Qt platform abstraction to make it easier to port apps written using Qt to new windowing systems. Threaded OpenGL support has also been added so you can have your app render OpenGL from more than one thread safely without having the main thread being blocked while the GPU carries out the rendering. This is achieved by using a separate thread that is only used to wait for the GPU.

Multithreaded HTTP has also been added, and HTTP requests are now handled in a separate thread by default. The release notes suggest that this will make application GUIs smoother, as networking will no longer use the main event loop.

The file system stack has been improved to reduce the number of system calls needed, and to make better use of any available cached data. This will provide better I/O performance no matter which platform you’re developing for.

The release also comes with an updated version of the QtWebKit open-source web browser engine with improvements to the HTML, CSS and JavaScript technologies.

The Qt VS Add-in 1.1.10 is also available, but this will be the last release from Nokia:"We’re happy to announce that the project has been handed over to Digia, Qt Commercial (http://qt.digia.com/) who offers commercial support and will take over future maintenance."